1. Field of the Invention
The present invention relates to a flow-down ice maker which produces ice by causing ice-making water to flow over an ice-making plate and cooling the ice-making water by means of an evaporator.
2. Description of the Related Art
FIG. 5 is a diagram showing the internal construction of the conventional flow-down ice maker disclosed in Utility Model No. 60-33182. An ice-making plate 3, over the front surface of which ice-making water flows and to the back surface of which an evaporator 2 is attached, is disposed at an inclined angle within a housing 1 composed of heat-insulating material. A sprinkler 4 is disposed along the top edge of the ice-making plate 3. An ice-making water tank 5 is disposed below the ice-making plate 3. The ice-making water tank 5 is shaped such that its lateral surface area decreases continuously towards the bottom (i.e., the tank is narrower at the bottom than at the top). Ice-making water is supplied to the ice-making water tank 5 from a supply pipe 8, which is provided with a supply valve 7. The ice-making water in the ice-making water tank 5 is conveyed to the sprinkler 4 by a pump 6. A water level detector 9, which detects prescribed upper and lower limits of water level, is disposed in the ice-making water tank 5.
As shown in FIG. 6A, the water level detector 9 comprises: a hollow pipe 10; an annular float 11 with built-in magnets (the flow which is guided by the hollow pipe and rises and falls according to the water level); and a water level upper limit reed switch 12 and water level lower limit reed switch 13. The switches are disposed in the hollow pipe and each open and close depending on the position of the annular float 11. When the water level in the ice-making water tank 5 reaches the upper limit H, the water level upper limit reed switch 12 closes a circuit which closes the supply valve 7 and initiates the ice-making process. The ice-making water then freezes on the ice-making plate 3. When the water level in the ice-making water tank 5 reaches the lower limit L, the water level lower limit reed switch 13 doses a circuit which terminates the ice-making process. In a flow-down ice maker of this type, the amount of ice-making water, which is bounded by the upper limit H and lower limit L of the water level in the ice-making water tank 5, corresponds to the amount of ice produced in one cycle.
However, when the foundation on which the ice maker rests is inclined from front to back or side to side, the housing 1 of the ice maker itself may be inclined from front to back or side to side, and the ice-making water tank 5 may therefore be inclined from front to back or side to side. For example, when the foundation is inclined from front to back with the back being lower, the ice-making water tank 5 is inclined as shown in FIG. 6B. In that case, the water level lines Lx, Mx, Hx, and Nx in FIG. 6B correspond in water volume to the water level lines L, M (a position between water level lines L and H), H, and N (a position above water level line H) in the ice-making water tank 5 when it is horizontal as in FIG. 6A
Consequently, for the water level detector 9 to operate at a prescribed water level (i.e., a prescribed water volume), it must be positioned along line Sx, which connects the points of intersection between water level lines L, M, H, and N and water level lines Lx, Mx, Hx, and Nx, respectively. However, because the water level detector 9 is conventionally positioned along line S, which is displaced significantly from line Sx, the water level upper limit reed switch 12 and water level lower limit reed switch 13 are activated above their prescribed positions, at points Nx and Mx, respectively. Furthermore, it should be clear from FIG. 6B that when the position of the water level detector 9 is to the right of line Sx in this drawing, the switches are activated below their respective prescribed positions. Moreover, in the case of this drawing, the shapes of the walls of the ice-making water tank 5 do not change in the vicinity of the upper limit H and lower limit L, and the difference .DELTA.H between Hx and H is therefore almost identical to the difference .DELTA.L between Lx and L. However, if the shapes of the walls of an ice-making water tank change in the vicinity of a given upper limit H and lower limit L, .DELTA.H and .DELTA.L may differ depending on the angle of inclination.
In conventional ice makers, no consideration has been given to the fact that the water level detector 9 may not work properly if the ice-making water tank 5 is inclined due to inclination of the foundation of the ice maker, etc. For that reason, the water level detector 9 is disposed in an arbitrary position, as in FIG. 6B, for example, and the amount of water used to make ice may be affected greatly by the degree of inclination of the foundation. Consequently, conventional ice makers suffer from the problem that the amount of ice-making water per cycle varies depending on the angle of the foundation, and therefore the size of the ice produced is inconsistent from machine to machine.